In one known three-dimensional coordinate measuring machine (hereinafter may be simply referred to as a coordinate measuring machine or contour measuring machine), the stylus tip (hereinafter may be simply referred to as a tip) of a touch probe is moved along the surface of a measurement object continuously to perform point-to-point measurement at predetermined intervals, whereby the surface contour of the measurement object is measured. Various types of styluses are used for the touch probe, and examples thereof include: a straight stylus shown in FIG. 1(A) in which a spherical stylus tip 14 is attached to the tip end (the lower end) of a shank 12; a disc stylus shown in FIG. 1(B) in which a disc-shaped stylus tip 16 is attached to the tip end of a shank 12; and a cylindrical stylus shown in FIG. 1(C) in which a cylindrical stylus tip 18 is attached to the tip end of a shank 12. The present applicant has proposed, in Patent Literature 1, a stylus with a flat end face as a modification of the disc stylus.